tmb 92mm f5.5? anyone

[sejanus (Gavin)]

Anyone used this scope? Is there a tmb dealer locally or is it just an import from the states thing? It's 2k usd for the ota overseas.

I've been looking at a few refractors and am going smaller now

Picking up the eq6 tomorrow but without a scope whilst I continue my analysis paralysis

[Craig_L]

Nearly bought an 80mm TMB. The 92 looks good. But no Australian distributor.

You should also look at the Tak Sky 90, which has a dedicated field flattener which gives you f4.5.

[sejanus (Gavin)]

thanks Craig

Theres so many good scopes in that range it makes my head spin

[Kal (Andrew)]

Hi Gav,

I remember replying to one of your posts on cloudynights the other day

From memory you will be using a full frame Canon Eos DSLR as an imager. This is quite a big chip to image with, and for imaging it places extra demands on your optics chosen. It rules out alot of small refractors, even ones with dedicated field flatteners, that will only offer a corrected flat field for up to APS sized chips - for example, my Stellarvie 90mm apo with it's SV flattener will only correct to APS sized chips - the 2" focuser isn't lareg enough. Generally for a full frame chip you will need larger than a 2" focuser, and larger than a 2" FF.

To correct for the full frame CMOS on the 1D I can't think of many short focal length apos that fit the bill. The petzvel refractors from Takahashi fit the bill (the FSQ-106 & FSQ-85) and also the petzvel refractors from Televue.

I can't see any information from TMB with regards to any dedicated FF for the 92mm scope. There may be aftermarket products out there that work, but you would want to find examples of how they work with a full frame chip before deciding on that scope.

The tak sky90 with the dedicated FF could be a good option. Takahashi america site is down atm for me, the only link I could find regarding the imaging circle it offers was a site in German that stated 44mm, which is just large enough for the 43.3mm diagonal of your cameras chip.

[Kal (Andrew)]

Originally Posted by sejanus

thanks Craig

Theres so many good scopes in that range it makes my head spin

Lots of good scopes, but not many scopes that are good at imaging on a full frame chip

[sejanus (Gavin)]

lol, yeah there are not many thats why I keep looking at scopes then changing my mind and going to another one when I (finally) manage to find a snippet of info about how they perform on a larger than APS sized sensor.

I ran up the tmb dealer in america and they were pretty dubious it would be any good on 35mm full frame. They were basically not sure.

So yeah, I keep looking at the taks. Then I think they are too much $$$ and look at every other brand under the sun. Then I go back to the taks again.

I'm about to have a look at televue's which was suggested to me today. Theres a 101mm that is a little cheaper than a fsq-106 - not by much though!

thanks for the info andrew

cheers

Gav